Combined Raman scattering and ab initio investigation of pressure-induced structural phase transitions in the scintillator ZnWO4

Abstract

Room-temperature Raman scattering was measured in ZnWO4 up to 45 GPa. We report the pressure dependence of all the Raman-active phonons of the low-pressure wolframite phase. As pressure increases new Raman peaks appear at 30.6 GPa due to the onset of a reversible structural phase transition to a distorted monoclinic b-fergusonite-type phase. The low- and high-pressure phases coexist from 30.6 GPa to 36.5 GPa. In addition to the Raman measurements we also report ab initio total-energy and lattice-dynamics calculations for the two phases. These calculations helped us to determine the crystalline structure of the high-pressure phase and to assign the observed Raman modes in both the wolframite and b-fergusonite phases. Based upon the ab initio calculations we propose the occurrence of a second phase transition at 57.6 GPa from the b-fergusonite phase to an orthorhombic Cmca phase. The pressure evolution of the lattice parameters and the atomic positions of wolframite ZnWO4 are also theoretically calculated and an equation of state reported.

38 pages, 6 figures, 5 tables

References in corpus (6)

• Pressure effects on the structural and electronic properties of ABX4 scintillating crystals
• Optical absorption of divalent metal tungstates: Correlation between the band-gap energy and the cation ionic radius
• Determination of the high-pressure crystal structure of BaWO4 and PbWO4
• High-pressure x-ray diffraction study of SrMoO4 and pressure-induced structural changes
• Effects of high pressure on the optical absorption spectrum of scintillating PbWO4 crystals
• Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

Cited by in corpus (5)

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• High-pressure structural phase transitions in CuWO4
• Pressure-induced phase transition and bandgap collapse in the wide-bandgap semiconductor InTaO4
• Evidence of nickel ions dimerization in NiWO${}_4$ and NiWO${}_4$-ZnWO${}_4$ solid solutions probed by EXAFS spectroscopy and reverse Monte Carlo simulations